Short answers, pulled from the story.
The word insect comes from a Latin root meaning cut, a description that has defined these creatures for over two millennia. Pliny the Elder introduced the term to the Latin world by calquing the Ancient Greek word entomon, which Aristotle used to describe life forms with notched bodies.
The oldest fossil that may be a primitive wingless insect is Leverhulmia from the Early Devonian Windyfield chert, dating back to a time when the first forests were just beginning to take shape. These early ancestors were small, soft-bodied, and fragile, yet they possessed a chitinous exoskeleton that would become the defining armor of the class.
In the Carboniferous age, the dragonfly-like Meganeura had a wingspan of up to 70 centimeters, a giant that ruled the skies of the Paleozoic Era. These ancient giants were possible because the atmosphere was thick with oxygen, allowing insects to grow to sizes that seem impossible today.
The value of insect pollination of crops and fruit trees was estimated in 2021 to be about 34 billion dollars in the US alone. Most flowering plants require an animal to do the transportation, and the majority of pollination is by insects.
At least 66 insect species extinctions have been recorded since 1500, many of them on oceanic islands. A larger 2020 meta-study, analyzing data from 166 long-term surveys, suggested that populations of terrestrial insects are indeed decreasing rapidly, by about 9% per decade.